Solar cells, also known as photovoltaic cells, are semiconductors that convert electromagnetic energy, such as light or solar radiation, directly to electricity. Photovoltaic energy conversion offers the perspective to provide for an environmentally friendly means to generate electricity.
However, at present state, electric energy provided by photovoltaic energy conversion is still more expensive than electricity provided by conventional power stations. Therefore, the development of more cost effective means for producing photovoltaic energy conversion units attracted attention in recent years. Amongst different approaches of producing low cost solar cells, thin-film silicon solar cells are regarded an important approach for achieving that goal.
A plurality of individual cells arranged on a common base and electrically connected is called a module, a solar module or a photovoltaic module, be it based on thin-film silicon or crystalline technology. Such modules are normally being grouped to larger installations, for example on roofs, building walls or on open grounds to constitute a solar power plant.
In view of this variety of fastening needs, the question of appropriate and cost-conscious fixation technologies becomes relevant, as the fixation technologies shall compensate forces coming from wind, rain, snow or alike. Further aspects for appropriate fixation technologies are easy maintenance and trouble-free replacement of damaged modules.
Various module fixation technologies are commercially available today. In order to fix the photovoltaic module, all these structures have in common the need for a well-designed supporting structure and tools to mount the photovoltaic module over the mentioned structure. This will not only sustain the weight of the module, but this will also provide possible fixation points in order to “clamp” and/or “screw” the module in such a way that the photovoltaic module can compensate wind and snow loads. The bigger, larger and/or heavier a photovoltaic module is, the more heavy and complex must be the structure to fix the photovoltaic module in a reliable way.
In most cases, a photovoltaic module is mounted in an inclined position. A substructure commonly used to mount the photovoltaic module comprises horizontal supports, for example a frame support at the edge and a middle support, so-called back rails, i.e. bars made from steel or aluminum profile, glued or clamped to a backside of the photovoltaic module. The clamps often grasp the edges of a module, eventually in connection with a frame enclosing the edges of the photovoltaic module. Such fixation avoids heavy back rails, but is not easy to maintain, as a lot of different parts are necessary to fixate the photovoltaic module to the support structure and several tools are needed for the installation of the photovoltaic module when using commonly known mounting techniques.
The main disadvantages are related to the cost associated to these structures, because the quantity of different materials used is quite high. In fact, a frame uses the whole photovoltaic module perimeter, a back rail twice the length or the width, depending on how it is fixed, of the photovoltaic module.